Hitherto, as industrial textiles, textiles woven by warps and wefts are widely used, for example, they are used in many fields other than a papermaking fabric, a belt for conveyance, a filter cloth, and so on, and textile characteristics suitable for applications and use environments are required. In particular, the requirement in the wire for papering used in a papermaking step in which sucking of a material or the like is performed using a mesh of a textile, is severe, a textile superior in surfaceability in which no wire mark of the textile is transferred to a paper, besides, one having together a rigidity of a degree in which it can be suitably used even under a severe environment, and a textile which can keep, for a long period, conditions necessary for manufacturing a good paper, are requested. Other than these, fiber supportability, improvement of the retention of papermaking, good drainage performance, wear resistance, dimensional stability, running stability, and so on, are requested. Further, in recent years, since a paper machine is made higher in speed, attendant upon it, also the requirement to the wire for papering becomes further severer.
In this way, if the textile for papering in which the requirement is severe among industrial textiles is described, since the requirement and its solution of most of the industrial textiles can be understood, hereinafter, the present invention representative of the papermaking fabric will be described.
For example, if the papermaking speed becomes a high speed, the sucking speed inevitably becomes a high speed, and there is a necessity of making the sucking power strong. By it, since cast-off of fibers, fillers, or the like, and generation of wire marks naturally become remarkable, further improvement of fiber supportability and surfaceability becomes necessary. If intrusion of a wet paper in the papermaking fabric becomes large, or sticking of a fiber is generated, also a problem that the wet paper exfoliation in case of transferring the wet paper to a felt becomes bad, arises. It is because, since the wet paper remaining on the textile and formed is, by the sucking power, pressed onto the textile upper surface, in the portion where a yarn is present, the yarn intrudes the wet paper, inversely, between meshes where no yarn is present, the wet paper intrudes the mesh and a mark of the yarn and mesh is generated on the wet paper surface. Although completely eliminating wire marks is impossible, for making this as small as possible and inconspicuous, the upper layer surface of the textile is made fine, and improvement of the surface smoothness and fiber supportability must be intended. However, since a fine mesh textile regarding the surfaceability and fiber supportability as important is fundamentally woven by yarns whose line diameters are small, it was inferior in wear resistance.
Furthermore, since the papermaking fabric runs at a high speed, on the running surface side on the side coming into contact with a machine, by friction with a roll or the like, a phenomenon that the textile gradually wears is observed, and there is also a case that the life ends the wear. To improve the wear resistance, various measures in which the textile texture is made into a texture of a weft wear type, or the material of the yarn is changed, are needed, in particular, a method of giving the wear resistance by using a yarn whose line diameter is large, or the like, is used in general. However, in the yarn whose line diameter is large, although the wear resistance is improved, it was difficult to obtain a superior surfaceability.
To solve both problems of the surfaceability and wear resistance, using two textiles constructed using different warps and wefts respectively in the upper surface side layer and the running surface side layer, a two-layer textile in which the textiles in both layers are united by connecting yarns has been used. In this method, there was an effect that the textile in accordance with the performance respectively required can be adopted. In the upper surface side layer, using warps and wefts small in line diameter, a fine upper layer surface was formed, and in the running surface side layer, using warps and wefts large in line diameter, a running surface large in wear resistance was formed. For the connecting yarns, in order not to decrease the surfaceability, in general, yarns of smaller diameter than the upper surface side warps and the upper surface side wefts were used. In the upper surface side layer texture, to form a fine surface, although, in many cases, plain weave is used, in practice, since the connecting yarns for weaving together the two layers are used, substantially, a surface in which the connecting yarns are disposed here and there on the plain weave surface is formed. Since, in the connecting yarns, portions appearing on the surface are also present, from the problem of the surface smoothness, it was not preferable to use yarns so large in line diameter.
Although, in many cases, as the textile for normal papermaking, a tension is applied in a warp direction, since the yarn in the warp direction is in a state that the tension is always applied, there is hardly a case that, by running of the textile, the warp is loosened and moves, on the other hand, in the connecting yarns which are, in many cases, disposed between wefts from the problems such as the weaveability and fiber supportability, if the tension is applied, it elongates or the connecting yarn is crumpled between the upper surface side textile and the running surface side textile and internal wear is generated, there is a case that a problem that a gap is generated between the textiles or separated arises. The internal wear is well observed in a connecting yarn small in line diameter and low in strength, used for improving the surfaceability. The connecting yarn cross-links with a yarn in the upper surface side layer for connecting the two textiles, since the yarn is drawn in by the connecting force, there was a problem that a concave is given to the upper surface side surface and the surfaceability of the textile is deteriorated.
Therefore, a development of a textile using a warp ground yarn connecting yarn in which the upper surface side layer and the running surface side layer are woven together with forming the upper surface side surface between the warps, has been made. As one example of this prior art, in Patent Publication No. 2-13072, an example of a two-layer textile characterized in that, even with connecting two layers of textiles by a set of two, it appears on a surface as one warp, and with a plurality of upper surface side warps, a plain weave texture is formed on the upper surface side surface, is shown in FIG. 1.
In this two-layer textile, since warp ground yarn connecting yarns are disposed in a set of two between warps to weave together the upper and lower two layers, although it is superior in connecting force, two knuckles of the warp ground yarn connecting yarn and the upper surface side warp are mixedly present, from the difference in texture or line diameter, or line material, of two vertical yarns, since the height of the knuckle of the upper surface side weft is different, it was impossible to form a smooth surface.